If the Drosophil melanogaster, with its unparalleled genetic versatility is to continue to flourish as a system par excellence for the investigation of problems in eukaryotic biology, then it is very important that information concerning the genetic raw material is in as complete and up-to-date form as possible. We propose to revise "Genetic Variations of Drosophila melanogaster," which has been in print for twelve years. We anticipate the addition of some 3,000 new entrees as well as updating many of the 4,500 entries in the first edition. We have accumulated the majority of the material needed for the revision since publication of the original. As an adjunct to material needed for the revising since publication of the original. As an adjunct to this project, which will be invaluable in revising the book, we propose to update and maintain the international crossindexed list of Drosophila melanogaster stocks, which we recently completed.